1. Field of the Invention
The present invention relates generally to deploying solar generator panels on a spacecraft such as a satellite in orbit around the Earth.
2. Description of the Prior Art
The expression xe2x80x9csolar generator panelxe2x80x9d refers to the set of plane structures of a solar generator having optical, thermal or photovoltaic active surfaces, and in particular:
panels supporting an array of identical or different photovoltaic cells converting solar energy into electrical energy,
reflector panels concentrating solar radiation onto the previous panels by means of a coating with appropriate properties, and
panels used for their thermo-optical surface characteristics (heat dissipators).
The panels of a thermal generator can be deployed in highly diverse configurations. Conventionally they form a longitudinal succession, parallel to a direction away from the body of the spacecraft, and around which the generator is adapted to turn to track the Sun. It has been proposed to provide additional lateral panels, over and above the panels previously referred to, to increase the available electrical power. There are also configurations known in the art in which the panels are disposed along a transverse direction, i.e. a direction which is transverse to the aforementioned longitudinal direction of the yoke connecting the generator to the body of the spacecraft, and around which the generator is adapted to turn to track the Sun.
During launch, the generator is folded and its panels are stacked in what is referred to as a stacked or stacking configuration.
Commissioning of the generator, for example when the spacecraft is a satellite and has reached its working orbit, involves unfolding the stack of panels, which is referred to as unstacking.
To go from the stacking configuration to the deployed configuration, in which the solar panels are in substantially the some plane, the panels are articulated two-by-two, either by means of articulations having adjacent members articulated about a pivot axis and each fastened to one of two adjacent panels, or by means of articulations connecting the parallel edges of panels, of the type described in the document FR-A-2 635 077.
The first-mentioned articulations are generally used to connect the panels of the aforementioned longitudinal succession (in-line panels). The articulations described in the document FR-A-2 635 077 are generally used to connect the lateral panels to the in-line panels.
In order to be able to lock the in-line panels in the deployed configuration, the panel articulations are generally provided with a locking mechanism including rotary immobilizing means mounted on a first of the two adjacent members and cooperating with the second of the two adjacent members to lock the corresponding two panels in the deployed configuration of the two panels. The immobilizing means are constrained to rotate with a lug which can rotate on the first of the adjacent members and temporarily locked against rotation by being abutted against a peripheral surface of a member constrained to rotate with the second of the two adjacent members. The peripheral surface has a configuration such that when the corresponding two panels reach the deployed configuration the lug escapes from the peripheral surface and pivots until the immobilizing means come into contact with the second of the two adjacent members in order to lock the two panels in the deployed configuration.
To prevent the panels colliding and being damaged during deployment, which could compromise the remainder of the mission of the spacecraft, a precise sequence of operations must be defined and carried out precisely.
In particular, the side panel or panels must not be released until the corresponding in-line panels have been locked in the deployed configuration, as this could impede the locking of those panels and cause disruptive impacts.
At present the sequence of operations is achieved in particular by synchronized deployment using pulley and cable conjugation systems. The use of cables can however constitute a single failure source, for example if the cables become jammed, with no possibility of redundancy. What is more, synchronized deployment of the various movements may prove difficult to achieve.
Another solution known in the art is to provide an electrical sequence using pyrotechnics devices on the successive panels whose function is to break links holding the panels in the stacking configuration. This solution has the drawback that the firing of such devices is generally a source of pollution affecting the subsequent performance of the panels and a source of sudden vibrations such that the panels and the connections between them must be highly rigid, which makes them heavy. Pyrotechnic mechanisms also require the use of command transmission cables which generate high cable resisting torques. Finally, pyrotechnics devices are generally heavy and bulky.
Consequently, the object of the present invention is to propose a mechanical (and therefore non-polluting) device for sequencing the deployment of one panel relative to other panels, in particular of a side panel relative to in-line panels, that is simple and therefore reliable, compact in size and light in weight, and has no significant resisting torque to that of the articulations linking the panels.
To this invention, the invention proposes an articulated system formed of at least three adjoining panels of a solar generator, articulated two-by-two to be able to pivot from a stacking configuration, in which the panels are stacked, to a deployed configuration, in which the panels are disposed in substantially the same plane, wherein two of the panels are connected together by at least one articulation having two adjacent articulated members each fastened to one of the two panels, a locking mechanism is mounted on the articulation and includes rotary immobilizing means mounted on a first of the two adjacent members and cooperating with the second of the two adjacent members to provide at least one-way non-return locking of the two panels relative to each other in the deployed configuration, the immobilizing means are constrained to rotate with a lug rotatably mounted on the first of the two adjacent members and temporarily locked against rotation by being pressed against a peripheral surface of a member constrained to rotate with the second of the two adjacent members, the peripheral surface has a configuration such that, when the deployed configuration of the two panels is reached, the lug escapes from the peripheral surface and pivots to bring the immobilizing means into contact with the second of the two adjacent members in order to lock the two panels in their mutual deployed configuration, and the locking mechanism further includes a first finger constrained to rotate with the lug and cooperating with a second finger fastened to the third panel to retain the third panel stacked on one of the two panels during movement of the two panels to the mutual deployed configuration, rotation of the lug on reaching the deployed configuration releasing the second finger and thereby enabling the third panel to move to a deployed configuration relative to the two panels after deployment of the first two panels.
A mechanical device having the advantages mentioned above can therefore achieve in-line and side panel deployment kinematics such that a side panel can open only if the two in-line panels are locked in the deployed position.
A system of the above kind could if required be transposed to the deployment of in-line panels relative to each other, for example.
In accordance with preferred, and possibly combined, features of the invention:
the peripheral surface is a cylindrical surface portion of a member adapted to rotate about a pivot of the two adjacent members,
the immobilizing means, the lug and the first finger are rotatable about a pivot substantially parallel to the articulation axis,
the second finger is fixed to a fitting mounted on and projecting from the third panel,
there is a clearance between the two fingers in the stacking configuration.
The present invention also proposes a spacecraft equipped with a solar generator formed of a plurality of panels including a deployment system in accordance with the invention.
The present invention will now be described in more detail with reference to the accompanying drawings.